Hydraulic control for variable delivery pumps



June 16, 1942. M, GE|GER 2,286,358

HYDRAULIC CONTROL FOR VARIABLE DELIVERY PUMPS I Filed Feb. 2, 1940 2,S heets-Sheet l Gzona! 04.6mm,

June,l6, 1942 5, M. GE|GER 7 2,286,358 I cbNTnoL I FOR ARIABLE DELIVERY PUMPS Filed Feb. 2, 1940 2 Sheets-Shee t 2 hydraulic motor.

Patented June l6, 1942- 2,286,358 HYDBAULIS CONTROL FOB VARIABLE ELIVEBY PUMP Geiger, Mount'Gilead, 01110, Development Corp. Inc., Wil- George M. to The Hydraulic mington, list, a corporation of Application February 2; 1940, Serial No. 316,956

5 Claims.

This invention relates to a hydraulic. control for a pump and more particularly to hydraulic 7 control for a reversible variable delivery pump for It is an object of vide automatic means for the control of a hydraulic pump whereby it is insured that the motive element of a hydraulic motor is continuously reciprocated, this motive element being reversed as it approaches the limit of its travel in one direction and likewise being automatically reversed at the end of its travel in the other direction so as to resume travel in the first direction.

Another object is to .provide a hydraulic control of the foregoing type wherein the rate of acceleration and deceleration at each end of the stroke may be adjusted to suit the desired conditions of operation.

Another object is to provide a hydraulic control of the type set out above wherein the speed of operation of the reciprocated member is adjustable in each direction to suit the requirements; the speeds in the two directions may be diii'erent if desired.

the present invention to proples of the present invention and being referred to hereinafter as the reciprocable member, Means is provided whereby the direction of application of hydraulic liquid to the double-acting hydraulic motor is reversed automatically at the end of each stroke. In thisway, continuous reciprocation of the motive element-is assured. In a preferred form, the control mechanism comprises a reversible variable delivery pump of known type which is provided withoppomteiy acting hydraulic motors for shifting the shift element thereof so as to reverse the delivery thereof, the input and pump being connected to opposite sides of the double-acting hydraulic motor which is to be controlled. A continuously operated pilot mum) is provided and means is provided for connecting the output thereof to either of the hydraulic motors for shifting the shift ring of the main pump. This means for connecting the pilot pump to operate the hydraulic servomotors of the main pump preferably takes the form of a four-way valve which is actuated in one direction at one end'of the stroke of the motive member to be Another object is to provide a hydraulic co"ntrol of the foregoing type which is simple and economical to build and in which the cost of operation and of maintenance are very low.

Another object is to provide a hydraulic con"- trol wherein means provided for stoppm the motion of the reciprocated member at the will of the operator. 1 p

Other objects will more fully hereinafter appear.

In the accompanying drawings;

Fig. 2 is an enlarged partially sectioned view Fig. 1 is a diagrammatic view showing the d etails of one embodiment of the present invention;

controlled and which isactuated in the opposite direction at the end of thestroke of the motive member in the other direction.

Preferably, means is provided in the form of variable restrictions in the conduits leading from the control .valve to the shifting servomotors for adjusting the rate of acceleration and deceleraof the reversible variable delivery pump employed in the embodiment of the invention shown in Fig. 1. g

Fig. 3 is a central vertical section through the pilot valve shown in Fig. 1 with the operating handle therefor removed. 1

Fig. 4 is a cross-section along the line 4-4- of Fig.' 3.

In accordance with the present invention, the mechanism to which it is desired to impart a reciprocating motion is operatively connected in any suitablemanner to the motive element in a double-acting hydraulic motor, this element being reciprocated in accordance with the princi- 'arypiston Ii and apairof of this type is that shown tion of' the motive member at each end of the 3 stroke.

Referring to the accompanying drawings in detail and first, more particularly, to Fig. 1, ll designates the reciprocatin cylinder of a doubleacting hydraulic motor which contains a stationstationary piston rods l2 and I3. This cylinder II is the reciprocable element and is connected in any suitable manner to the machine or be given reciprocating motion. For example, cylinder II might be connected to reciprocate the cutting tool of a shaper or lathe. While the embodiment shown'in theorawings involves a reciprocating cylinder and piston rods, 11-. will be desired the cylinder might be the piston caused to reciprothe operation of cylinder II is supplied by a radial variable delivery re;- versible main pump J4. This main pump II is of-atypeknowntothose skilledintheartandits construction does not per se constitute any part of the present invention. For example, a pump in Ernst Patent No.

understood that if held stationary and cate. Pressure fluid for output to this reversible other device which isto e 2,021,353. Referring to Fig. 2 it will be seen that this pump |4 embodies a shift ring l5 which is movable transversely of the pump so as to vary the amount and direction of delivery of the pump, shifting of ring l5 being accomplished by the shift rods I6 and H which are threadedly received within the shift ring l5 and which are slidable relative to the casing of the pump i4.

In order to actuate the shift rods l6 and I1, there is provided instead of the usual single hydraulic motor and spring-loaded opposing plunger located on opposite sides of the pump, a pair of hydraulic motors having cylinders l8 and 9 respectively and hydraulic pistons 20 and 2| respectively. It will be seen that the two hydraulic motors thus formed constitute in effect a doubleacting hydraulic motor for reciprocating the shift ring l5. It will further be seen that when shift ring I5 is shifted to the left of Fig. 2 as shown in that figure by the application of fluid pressure on the right-hand of piston 2|, the delivery of pump 4 is in one direction, and .when the ring I5 is shiftedrightwardly by the application of fluid pressure to'the left-hand of piston 29. the direction of delivery is reversed.

Since pump l4 in addition to being reversible in delivery is variable in delivery in either direction, means is provided for individually adjusting the amount of delivery in each direction of delivery. This means takes the form of adjusting screws 22 and 23 provided for control cylinders l8 and I9, respectively, these adjusting screws being adapted to engage reduced portions 24 and 25 respectively of pistons 20 and 2|, which reduced portions extend outwardly and are slidaably received with the-outer portion of cylinders l6 and I9. The actuating hydraulic liquid for control cylinders l8 and I9 is admitted by means of conduits 26 and 21 respectively, which connect rzvlith the space behind the control pistons 20 and The main pump I4 is provided with fiuid'connections 28 and 29, each of which is adapted to act either as an inlet or as an outlet for pump l4, depending upon the direction of delivery thereof. Connected to these members "and 29 are conduits 39 and 3|. Conduit 35 is in constant communication with the pressure chamber formed in the right hand of cylinder I! by means of a T-shaped member 32 and a..bore 33, and

continues beyond member 32 into commimication with a liquid reservoir 34 through a check valve 35 which is adapted to allow liquid to flow from reservoir 34 into connection 23 of pump M by way of conduit 30 but to prevent the reverse flow main pump regardless of the direction thereof. This means may take'the form of conduits 4| and 42 connected to the conduits 30 and 3| respectively and leading to the two-way valve 43 which has a piston 44 adapted to be reciprocated so as to place conduits 4| and 42 into or out of communication with one another. This valve 43 may be operated either manually or automatically, as desired.

Liquid pressure for effecting the operation of control cylinders l8 and I9 is generated in a pilot pump 45 which is of any suitable type such as the positive displacement gear pump diagrammatically illustrated in Fig. 1, this pump drawing liquid from tank 34 by way of conduit 45 and discharging the liquid under pressure into conduit 41. A relief valve 48 is provided in conduit 41 for leading the output thereof back to the tank 34 by way of the conduit 49, after the control has been effected. Pilot pump 45 delivers pilot pressure through conduit 41 to the four-way valve 59 which may be of any suitable type, such as that shown in Figs. 3 and 4, and which is adapted to deliver the pressure liquid supplied to it by conduit 41 either to conduit 26 leading to control cylinder l8 or to conduit 21 leading to control cylinder 9, depending upon the position of the rotatable gate in valve 59, and at the same time to connect the other conduit 26 or 21 which is not connected to conduit 41 to the tank 34 by means of a return conduit 5|.

Disposed in conduit 26 is a check valve 52 which is adapted to allow liquid to flow freely from valve 59 into the control cylinder l6 but to prevent the reverse flow. The reverse flow is compelled to take place through an adjustable choke valve 53 which is in parallel with check valve 52 and which is adjusted to impart a suitable restriction to the outflow of oil from cylinder l8 back to the tank 34 and to thereby control the rate of acceleration and deceleration at the end of the rightward stroke of cylinder l0.

Conduit 21 is likewise provided with a check valve 54 allowing free passage of oil from valve into cylinder |9 but compelling the reverse flow of oil to take place through a restriction 55 of liquid whereby when pump M is delivering its output into conduit 30, the output is compelled to enter into the pressure chamber at the right hand of piston The conduit 34 is provided with the usual safety valve which is adapted to open upon the attainment ofan excessive pressure in line 33 to allow discharge therefrom into tank 34.

The other conduit 3| extends from connection 29 to a r-shaped member 31 carried on the end of piston rod |2 into communication with the space on the left hand of piston by way of bore 38 in piston rod 2, and extends beyond the member 31 into tank 34 from which it is adapted to draw liquid by way of check valve 39 which is "likecheck valve 35 described above. A safety valve 40 is provided for conduit 3|, this afety valve corresponding to the safety valve 36.

In order to stop the movement of cylinder III, means is provided for bypa-ing the output of which is similar to restriction 53.

The valve member 56 of four-way valve 53 has a shaft 51 to which is fixedly attached in any suitable manner a two arm control member having arms 58 and 59 mounted fixedly at the desired angle with respect to one another and with respect to valve member 56. In order to actuate the valve member 56 so as to reverse the application of the output of pilot .pump 45 from control cylinder |3. to control cylinder l9, or vice versa, at the ends of the stroke of cylinder II, a valve shifter rod 69 is fixedly mounted on cylinder l6 atany desired position. Preferably, the longitudnial position of shifter rod 63 is adjustable in any suitable manner, for example, as indicated in Fig. l, by providing a series ,of longitudinally spaced threaded holes 13 in the periphery of cylinder It. In this way, the stroke of cylinder ||I can be addustedr As is apparent, the shifter rod is adapted to engage the control arm 59 at the end of the leftward stroke of cylinder l9, thereby shifting valve 50 so as to cause the application of the output of pilot pump 45 to the other control cylinder l8, whereby to shift the direction of delivery of main pump l4, causing reversal of the application of the output of pump l4 and causing reversal of the direction of cylinder Ill, As cylinder Ill approaches the limit of its rightward travel, shift rod 60 is cylinder leakage will be greater.

- valve 50 as illustrated in 'located within the tank 34. This valve is of the type disclosed as elements 16 to 21 in Ernst, United States Patent No. 1,653,350 and comprises oppositely disposed end chambers connected to from the cavity-formed by curved exhaust port 64. A longitudinal passageway 65 connects the forward portion of the valve member to.the exhaust passageway 62 in order to prevent pressure building up on the end surface of valve member 56 due to leakage. Circumferentially; the pressure is equalized by the crosspassages 6| and 62 and by admitting pressure surface 69 to the exactly similar cavity." on the opposite side of the-valve member through the circumferential grooves 12 which extend around the sides'of the conduits 30 and 3| and separated by a. central 1 chamber in constant communication with the oil" in tank 34. The communication between the central and end chambers is controlled by a valve member 12 having spaced valving heads and being so arranged that when either end chamber is.

in communication with the central chamber the other end chamber is out of communication with the central chamber. The purpose of'this shuttle valve ll is to take care of difference in displacements between the two ends of the cylinder III. This difference in displacement may be due to the use of cylinders of different diameters or of'a double-acting cylinder II) with different diameter rods l2 and I3 or through more leakage from one sideof piston than from the other.

Assume that the left-hand side of cylinder II) has a larger displacement than the right-hand side due tosome cause. For example, assume that piston rod I2 is smaller than piston rod |3 for obtaining a slower travel of cylinder l0 leftwardly than rightwardly. When pressure is applied to conduit 3| to move the cylinder Ill leftwardly this pressure will immediately cause the valve member 12 in shuttle valve II to move rightwardly, cutting on communication of conduit 3| with tank 34 and establishing communication of conduit 30 with tank 34 in addition to that provided by the check valve 35, allowing oil to pass freely into conduit 3|! and thence into the pump M to meet the demands thereof which will exceed the amount of oil being forced out of the right-hand side of cylinder III. Now when pros sure is applied to conduit 30 to force cylinder l0 rightwardly, the volume of oil squeezed or forced out of the left-hand of cylinder'lll will be greater than that demanded by pump l4 and will have no place to go were shuttle valve 'I| not provided. Shuttle valve 1| allows this excess oil to pass back to the tank 3|, the valve element 12 thereof having been moved leftwardly. to this end by the pressure developed in conduit 30.

Shuttle valve H is absolutely necessary only in one direction of movement of cylinder Ill because of' the provision of "check valves .35 and 39. However, in order to supply a standard system adapted to meet any conditions of operation or installation, it, is preferred to supply the conventional double-acting shuttle valve. For example, it cannot be predicted on which side of provided with a recess 53 communicating with an Also, it is valve member 56 at the left-hand of Figure 3.

The valve casing is provided with an inlet port 36 which is connected to the inlet conduit 41 and with a pair of service ports 61 and 68 which are connected respectively to the conduits 26 and 21. The valve member 56 also has a curved portion 69. The exhaust port 64 is connected to the return line 5|. The flatcylindrical space H behind valve member 56 is in communication with exhaust space 63 and with the longitudinal exhaust passageway 10 which communicates with the exhaust bores 6| and 62.

If the shaft 51 of the valve is rotated so that the passage 6| communicates with the service outlet '61, then pressure fluid is admitted from inlet conduit 4'| and passes outwardly through the service outlet 68 to the conduit 21 and to control'cylinder 19. At the same time. the service outlet 61 is connected to the central passageway 10 leading to the exhaust passageway 63 and thus to the exhaust port 64 and to the return line 5|, connecting conduit 26 and control cylinder I8 back to the tank 34. If the shaft 51 is reversed and rotated so as to place passage 62 beside service port 68, the inlet conduit 41 will be con- Operation In the position shown in the drawings, the stroke adjusting ring l5 of the main pump M has beenshifted to the full stroke position to the left. This was accomplished by shifter rod shifting the control arms in a clockwise direction,

verted from line 21 to line 26. This shifting in causing the output of pilot pump 45 to enter the conduit 21 and the control cylinder l9, causing the control pistons 2| to shift the ring l5 leftwardly. As this occurred, the liquid in control cylinder l8 was discharged through the conduit 26 by way of the choke valve 53 to the control valve 50 and thence through conduit 5| back to the oil reservoir 34. Consequently, the radial pump I4 is delivering pressure fluid through line 3| to the left end of cylinder Ill, causing cylinder ID to move leftwardly. As shown, cylinder I0 is approaching the end of its stroke in the left hand direction and the valve shifter rod 60 has come into contact with the arm 59 of control valve 50. Further movement of cylinder to the left will move arm 59 counter-clockwisecausing the delivery fromvpilot pump 45 to be dipressure will move the shift ring of pump H to the right, the liquid to the right of control piston 2| being discharged outwardly through restriction 55 back to the tank 34, thus causing a gradual reduction in the pump stroke; causing the pump stroke to pass through neutral and causing the pump stroke to be shifted so as to deliver oppositely.

As the pump I4 passes through the neutral position, the cylinder I reaches the limit of its leftward movement, and as the pump I4 is now on stroke in the opposite direction so as to deliver into conduit 30 and suck oil from tank 34 through conduit 3|, the output of pump I4 is now delivered to the right-hand side of piston II and causes cylinder I0 to begin moving towards the right-hand. As cylinder I0 reaches the limit of its rightward travel, its shifter rod 60 will contact control arm 58 and will shift the pilot pump I4 back to the position shown in the drawings.

From the foregoing, it will be noted that the control pressure liquid being supplied to a control cylinder I8 or I9 has free access through a check valve andthat the liquid making its exit from the other control cylinder has restricted flow outwardly through a check valve. This is true for either reversal of the pump I4. No attempt is made to control the flow of control pressure liquid to a control cylinder I8 or I9 but the control of the spaced reversal of pump I4 is' effected solely through controlling the discharge from the control cylinder on the opposite side' of the pump I4. For example, when the control liquid pressure is being supplied to cylinder I8, the discharge from cylinder I9 must all go through choke valve 55 which-"can be adjusted to slow down the movement of the pump shift ring I by any desired amount. Similarly, when the control liquid is being applied to the cylinder I9, the discharge from the cylinder I8 must all go through choke valve 53. Choke valves 53 and 55 may be individually adjusted so as to give a different restriction to fluid f low'therethrough and in this way the rate of deceleration and acceleration at one end of the stroke of main cylinder I0 may be made different from the rate of deceleration and acceleration at the other end of its stroke. Thus, a different cushioning action is possible. In other words, it is possible to produce an operating stroke having a very high acceleration and a very slow deceleration and aretum stroke having a slow acceleration and a high deceleration or the opposite by mere manual adjustment of restricting valves 53 and 55.

It will further be noted that by adjustment of the adjusting screws 22 and 23 provided'for the control cylinders, it is possible to limit the delivery of the pump I4 in either or both directions and thus to limit the maximum operating speed of cylinder I II in either or inboth direc- ,by-passed.

Itwill further be noted from the foregoing.\

that when pump I4 is delivering into conduit 3|,

this pressure liquid so delivered is effectively applied to cylinder I0 since it cannot return to the tank 34 However, when conduit 3| is the suction conduit, liquid is sucked bothfrom tank 34 through checkvalve 39 and from the space at the left-hand of piston II. The same is true of theother conduit 30 with appropriate changes in the reference characters.

:While in the foregoing description the shifter rod is shown as a hook for contacting the control arms 58 and 59, it might equally well be a control rod with cams. or an arm, or an oil ac- .tuated plunger, or a pair of limit switches, any

of which could be positioned so as to actuate a torque motor connected to the pilot valveshaft 51 of valve 50. The actuation of apilot yalve by means of a torque motor adapted to operate in continuous stalled service is disclosed in the copending application of W. R. Tucker, Serial No. 167,184 filed October 4, 1937.

It will further be noted that by adjusting the control arm 60 longitudinally relative to the cylinder III, the stroke of cylinder III in one direction may be varied relative to the stroke of cylinder I II in the other direction. In other words, if arm BI! is moved from its present position relative to the cylinder III to the next following position numbered I3, the extreme left hand position of cylinder III on its leftward stroke will be shifted toward the right by a distance equalling the distance between the present position of arm 60 and the said next following position numbered 13.

It will be understod that the pump I4 is still on stroke after the valve 50 has begun to be shifted because the pressure in the then effective servomotor cylinder I8 or I9 cannot escape. Accordingly, the output of pump I4 will continue to move the cylinder I0 so as to shift the valve 50 to neutral and slightly beyond, whereupon the then effective servomotor cylinder I8 or III will be connected slightly to exhaust. The connections to exhaust and to intake are effected simultaneously in the same amount by the valve member 56. The pump I4 will now begin to shift slowly towards neutral, not being able to shift rapidly because the slight connection to exhaust operates as a restriction on the discharge of fluid from the then effective servomotor cylinder. Accordingly, the pump I4 will continue on stroke so as to move the cylinder I0 still further until'it'shifts valve 50 sufficiently and a sufficient period of time has elapsedto allow emptying of the previously effective servomotor cylinder and filling of the opposing servomotor cylinder to an extent sufllcient to shift pump I4 through neutral onto stroke in the other direction.

I wish it to be understood that I intend to include as within this invention such modificatio'ns as may be necessary to adapt the same to varying conditions and uses and as fall within the scope of the appended claims.

Having thus fully described my invention, what I claim. as new, and desire to secure by Letters Patent is:

1. A hydraulic mechanism comprising a reversible-delivery liquid pump, reciprocable means for reversing the direction of delivery of said pump, a hydraulic motor having a motive element operatively connected to move said reciprocable means in one direction, a second hydraulic motor having a motive element operatively connected to move said reciprocable means in the other direction, a source of fluid pressure; and valve means for selectively connecting said fluid pressure to one or the other of said motors, and control means interposed between said valve means and each of said hydraulic motors and adapted to allow unrestricted flow of fluid from said valve means to each of said hydraulic motors, while permitting only a restricted flow from each of said motors to said valve means.

2. A hydraulic mechanism comprising a reversible-delivery liquid pump, reciprocable means for reversing the direction" of delivery of said pump, hydraulic motdr means movable in opposite directions and operatively connected to said reciprocable means for actuating the latter. a

source of fluid pressure, valve means for selectively connecting said source of fluid pressure to one or the other side of said motor means, two chokes respectively interposed between said valve means and each side of said motor means for restricting the flow oi 'fluid from said motor means to said valve means, and means associated with each of said chokes and adapted responsive to the flow of fluid from said valve means to said motor means for making the respective choke ineiiective.

3. A hydraulic mechanism comprising a re-- versible-delivery liquid pump, reciprocable means for reversing the direction of delivery of said pump, a pair of hydraulic motors oppositelysoperatively connected to said reciprocable means,

a source of fluid pressure, a pair of conduit means, each of which connects to one of said motors, valve means for alternatively connecting said source .to either of said conduit means, and adjustable choke means respectively arranged in each of said conduit means for restricting the flow of fluid from said fluid pressure source to either of said motors, and two check valves respectively associated with said conduits for short circuiting the choke means of one of said conduit means, while the choke means of the other conduit means is effective. a

4. A hydraulic mechanism comprising 'a reversible-delivery liquid pump, reciprocable means for reversing the direction of delivery of said pump, a pair of hydraulic motors oppositely operatively connected to said reciprocable means,

means, each of which connects to one 01. said motors, valve means for alternatively connecting said source to either of said conduit means, a pair oi'adjustable choke valves respectively arranged in said conduit means for restricting the flow of fluid from said motors to said valve means, and a pair of check valves respectively lay-passing said choke means and responsive to the supply of pressure fluid from said source of fluid pressure to said conduit means to allow free passage of fluid from said source to said motors.

5. A hydraulic mechanism comprising a reversible-delivery liquid pump, reciprocable means for reversing the direction of delivery of said pump, a pair of hydraulic motors oppositely operatively connected to said reciprocable means, a source of fluid pressure, a pair of conduit means, each of which connects to one of said motors, means for alternatively connecting said source to either of said conduit means, means in each of said conduit means for allowing i'ree passage of fluid to the hydraulic motor associated therewith and for preventing the reverse flow of liquid, restriction means in parallel with each of said last-named means for restricting the flow oi fluid when said flow is from said hydraulic motor, and a pair of pump stroke adjusting means respectively associated with said hydraulic motors for independently varying the pump stroke in either direction,

' GEORGE M. GEIGER.

a source of fluid pressure, a pair of conduit- 

